This invention generally relates to watercraft and more specifically to electric watercraft and control systems for stabilizing watercraft.
One problem with the concave xe2x80x9cvesselxe2x80x9d design of watercraft is that excess watercraft volume is required above the water line to accommodate weight shift and to prevent catastrophic failure from water spilling into the vessel. That is, an open displacement vessel must have a large volume that increases from its bottom to top and that presents a vertical or concave shape, which creates a maximum of friction at the water surface. Such a concave hull efficiently transmits and receives energy to and from the water surface. The hull loses energy to the water and creates a wave (wake) simply by moving. The wake increasingly impedes boat movement as the boat acquires velocity, and becomes a standing wave at what is known as a limiting xe2x80x9chull-speed.xe2x80x9d Conversely a displacement vessel absorbs wave energy and is easily rocked by waves. Because of this sensitivity to waves a traditional xe2x80x9cpersonalxe2x80x9d watercraft that typically is less than 30 feet long, and particularly less than 25 feet long often cannot be used in the ocean when large waves are present. To overcome the large wave problem, a vessel type of watercraft simply is made larger. However, this solution is impractical for personal watercraft, especially trailorable watercraft that are limited in size by the dimensions of vehicles that can travel behind a car or truck on a highway.
The drawbacks of the traditional vessel displacement hull design are worsened when combined with electric propulsion systems. Boats that rely on rechargeable batteries, (which includes fuel cells in this context) have to carry a heavy and bulky power source. The great weight of the power source requires yet a larger hull to displace a larger volume of water to keep the boat afloat. This interferes with hull streamlining and can make the boat larger to accommodate the power source. Thus, the development of electric watercraft technology in particular is hindered by the vessel hull problem. In fact, the vessel hull drag prevents economical use of electric motors that utilize batteries for even moderate speed (above 8 mph) boating. This unfortunate state of affairs is a well known problem with electric boats, as, for example, stated in DOUGLAS LITTLE, ELECTRIC BOATS, THE QUIET HANDBOOK OF CLEAN, QUIET BOATING, (International Marine, 1994) on page 33 (referring to propeller design): xe2x80x9cIn the case of the electric boat, high speedxe2x80x94above 10 mphxe2x80x94is one factor that can be dropped immediately.xe2x80x9d Clearly, new designs are needed for wide acceptance of electric boats as general-purpose personal watercraft.
There is no comprehensive combination approach to this problem that plays off some disadvantage(s) of using heavy batteries or other low energy density power source with other disadvantage(s). In particular, no design strategy has successfully exploited the large mass and volume requirement of electric (including fuel cell) batteries as an asset, instead of a demerit, in a boat structure. Finally, there is no sufficient design for an electric powered and trailorable watercraft that can withstand moderate wave activity such as 2 feet high waves, without requiring a large vessel that cannot easily be pulled behind a car. A solution to these problems would open up new areas of boating to those that cannot buy or use the much greater size boats needed during moderate wave activity.
The inventors discovered a way to exploit the heavy battery problem in an electric boat design that simultaneously (i) allows use of massive battery power for a small watercraft, (ii) stabilizes the watercraft, partly by decreasing its center of gravity, (iii) decreases resistance to wave action and (iv) decreases friction to boat movement. From this discovery, the inventors have discovered new types of electric watercraft having advantages of high speed operation (above hull speed), diving capability, for example with an air filled chamber, and sailboats having low center of gravities but that can enter shallow waters.
Pursuant to their investigation, the inventors also discovered that arranging one or two primarily submerged closed hulls with at least one surface piercing strut works poorly for a personal watercraft but that they could make the platform shorter or add one or two floating skis to provide the needed stability. That is, while studying how to overcome the problem of transmitting and receiving surface energy, new features and modifications were found that improve watercraft by exploiting the advantage of using a heavy power source.
In one embodiment, the invention is an electric powered watercraft capable of exceeding its calculated hull speed, comprising at least one elongated submerged support member having convex upper surfaces and at least one strut attached to the upper surface, a propulsion unit and a low energy density power source within the at least one support member, at least one float having at least one strut attached to the upper surface, and a platform attached to and positioned above the top of the struts from the support member(s) and float(s).
In another embodiment the invention is an electric powered watercraft capable of both cruising at the water surface and diving, comprising two elongated submersible support members with at least one strut attached to the upper surface of each support member, a propulsion unit and a low energy density power source within each support member, and a platform attached to and positioned above the struts of the support members, the platform comprising a cabin with an opening at its bottom that allows divers to enter and exit the cabin at ambient pressure, wherein at least the top of the cabin is held above the water surface during cruising at the water surface and the entire cabin submerges during diving.
In yet another embodiment the invention is a non-vessel type watercraft less than 40 feet in length, comprising at least one support member having at least one strut at its top surface, a platform attached to the strut of the support member and held above the support member by a distance, and a means for preventing submersion of the platform. In related embodiments the means for preventing submersion of the platform is selected from the group consisting of: a horizontal rudder operably connected to a movable deflector, the movable deflector affixed to the watercraft above the waterline; a passive mechanical force deflector affixed to the front half of the watercraft and that automatically pulls the front of the watercraft up upon collision with waves; a bow-mounted propeller having a thrust that inclines and that is controlled by a submersion monitoring system; monitoring watercraft depth electrically or optically and compensating by stopping the watercraft, decreasing the watercraft speed, shifting weight distribution in the watercraft and/or steering the watercraft to compensate the detected vertical movement; an inclined surface at the leading edge of the platform that forces the watercraft up upon collision with the water; and floatation material within the platform.
In another embodiment the invention is a watercraft that comprises a computer that monitors the attitude of the watercraft and/or wave activity by gathering data concerning water movement detected with respect to a position on the watercraft via an electronic device. In particular embodiments, the data is gathered from at least 3 positions on the watercraft and used to obtain both speed and direction information for wave activity. In yet another embodiment the invention is a software implemented method that uses such sensor information to determine water surface conditions, and may even determine the development of storms, and use that information to guide the boat away from storm activity.
In another embodiment the invention is an enhanced solar reflector that uses a surface of reflective material to enhance solar panel electrical output while minimizing interaction of wind with the solar reflector. In specific embodiments thereto, the reflector comprises slats that rotate to optimize collection of solar energy from a moving sun, in an embodiment the slats respond to wind gusts by moving into a position that allows easier wind passage through the reflector, and in another embodiment the reflector comprises a porous fabric.
In another embodiment the invention is a houseboat less than 45 feet long that has a low center of gravity and which can cruise on the ocean.
Other embodiments will be appreciated from their descriptions in the specification.